First, apologies if the thread has become confused. My particular problem was the Surface Pro 3 (win 8.1) losing the connection to the MS Universal keyboard. It works fine at home, and failed here at work. I spoke to the guy who runs our wireless, changed my WiFi connection to 5Ghz, and it now works reliably.
So I take it back, Microsoft DO seem to have implemented a wireless solution where the Bluetooth and WiFi can't play together nicely. The router is still broadcasting 2.4 GHz, so it seems the Surface Pro's receiver isn't selective enough, or its transmitter is bleeding.
My thanks to those on the forum who raised this. I like the keyboard enough so I'll keep it and accept that it wont work on a 2.4Ghz WiFi.
Now how Do I tell Amazon to cancel my return...?